Automatic control system for radioactive regional ventilation studies

ABSTRACT

A system for obtaining a permanent visual record of the air passages of the lungs by the introduction of a measured quantity of air mixed with a radioactive gas such as Xenon (Xe133) into the lungs of the subject. A conventional scintillation camera or other radioactive recording device is operated to produce a permanent visual record. A separate air reservoir provides nontagged air to fill the breathing passages and confine the radioactive tagged air to the lungs. The apparatus operates in sequence to supply the desired quantity of radioactive tagged air from a reservoir, followed by the measured quantity of ordinary air from a second reservoir, and then prevents exhalation during the time period necessary for the radioactive recording device to operate. The supply of premeasured quantities of tagged air and additional air insure that the subject will take only a normal size breath. Ganged stepping switches and a timing device provide automatic sequencing. A modified form of the apparatus utilizes a flexible wall radioactive gas reservoir and an associated pivoted lever which drops down to actuate a microswitch and open the valve to the additional air when the radioactive gas reservoir is depleted. A method is described in which measured quantities of tagged air and additional air are sequentially applied to the subject, exhalation is prevented during the period in which the radioactive recording is made, and exhalation is thereafter permitted.

ijnited States Patent Suprenant et al.

[4 1 May 30,1972

[54] AUTOMATIC CONTROL SYSTEM FOR RADIOACTIVE REGIONAL VENTILATIONSTUDIES [72] Inventors: Edgar L. Suprenant, 4729 Firmament Avenue,Encino, Calif. 91316; Harold F. Rieth, P. O. Box 2102, Costa Mesa,Calif.

92626; Clayton H. Douglas, 30489 Amber Sky Drive, Palos Verdes, Calif.90274 22 Filed: July 8,1970

21 Appl.No.: 53,211

Primary Examiner.lames W. Lawrence Assistant Examiner-Morton J. FromeAttorney-Schapp and Hatch ABSTRACT A system for obtaining a permanentvisual record of the air passages of the lungs by the introduction of ameasured quantity of air mixed with a radioactive gas such as Xenon (Xeinto the lungs of the subject. A conventional scintillation camera orother radioactive recording device is operated to produce a permanentvisual record. A separate air reservoir provides non-tagged air to fillthe breathing passages and confine the radioactive tagged air to thelungs. The apparatus operates in sequence to supply the desired quantityof radioactive tagged air from a reservoir, followed by the measuredquantity of ordinary air from a second reservoir, and then preventsexhalation during the time period necessary for the radioactiverecording device to operate. The supply of premeasured quantities oftagged air and additional air insure that the subject will take only anormal size breath. Ganged stepping switches and a timing device provideautomatic sequencing. A modified form of the apparatus utilizes aflexible wall radioactive gas reservoir and an associated pivoted leverwhich drops down to actuate a microswitch and open the valve to theadditional air when the radioactive gas reservoir is depleted. A methodis described in which measured quantities of tagged air and additionalair are sequentially applied to the subject, exhalation is preventedduring the period in which the radioactive recording is made, andexhalation is thereafter permitted.

9 Claims, 4 Drawing Figures Pakmnked may 30, 1972 3,666,955

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506/? L. SUKPKENANT LU F. R I 5 TH TUN H. DOUGLAS INVENTORS BY 501% zeidfi ATTDKNEVS BACKGROUND OF THE INVENTION This invention relates to anAutomatic Control System For Radioactive Regional Ventilation Studies,and more particularly to a method and apparatus to facilitate the makingof a permanent visual record of the air passages of the lungs with ascintillation camera or other radioactive recording device responsive toradioactive emissions from a quantity of radioactive tagged gas breathedinto the lungs by the subject.

Radioactive ventilation studies have proven to be valuable as adiagnostic tool. However, a number of problems have been encountered inthe techniques used heretofore. A major problem results from thenecessity of performing a number of mechanical operations in the propersequence in less than a minute.

The proper quantity of radioactive tagged gas must be supplied to thelungs of the subject, and an additional quantity of air representing thetidal capacity of the subjects breathing passages should be placed insuch passages, the breath must be held during the period of timenecessary for the radioactive recording device to operate, and theexhaled radioactive tagged gas must be removed. Provision must be madeto seal the system against escape of the radioactive gas, and the studymust be made as comfortable as possible for the subject, who may be inpoor physical condition.

SUMMARY OF THE INVENTION The automatic control system of the presentinvention includes provisions for overcoming the recited difficulties byautomatic sequencing of the procedures in a manner providing consistentand reproducable results. In order to simplify the operation, thecomplete procedure is operated from a compact control box, andpreferably can be automatically programmed to cycle through the desiredsequence.

It is important that, during the radioactive regional ventilation study,the patient take only a truly normal breath. A larger than normal intakeexpands the lung passages and the resulting scintiphoto thus indicates afalse lung condition. Likewise, a smaller than normal intake produces aninaccurate indication of the lung condition of the patient. It is alsoadvantageous to maintain the lung area in the normal size because of thenormally limited camera coverage area available.

It is also an advantage during the radioactive regional ventilationstudy to concentrate the radioactive gas and restrict it solely to thelungs. In the present invention, this is accomplished by limiting themeasured radioactive gas volume to the volumetric capacity of the lungsduring a normal breath, and thereafter adding a measured quantity ofnormal air equivalent. to the volumetric capacity of the breathingpassages leading from the mouth to the lungs.

The present apparatus is capable of sequential operation either manuallyor by automatic cycling. In either case, the controls are interlocked toassure the desired sequence of operation.

Accordingly, it is an object of the present invention to provide anapparatus for conducting radioactive regional ventilation studies inwhich a measured quantity of radioactive tagged gas is supplied to thelungs of the subject in a manner simulating normal breathing action.

Another object of the present invention is to provide an ap paratus ofthe character described in which the radioactive tagged gas is confinedto the lung area by filling the breathing passages from mouth to lungwith a measured quantity of normal air.

A further object of the invention is to provide an apparatus of thecharacter described in which exhalation is prevented during the timenecessary to operate a radioactive recording device.

A still further object of the invention is to provide an apparatus ofthe character described which operates automatically in a desired timedsequence.

Yet another object of the present invention is to provide a method ofconducting radioactive regional ventilation studies in which measuredquantities of radioactive tagged air and normal air are sequentiallysupplied to the lungs and breathing passages of the subject at ambientpressures and in a manner closely approximating a normal breath, withexhalation of same being prevented during operation of a radioactiverecording device.

Other objects and features of advantage will become apparent from thefollowing specification and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The preferred forms of the inventionare illustrated in the accompanying drawings fonning part of thisspecification, in which:

FIG. 1 is a schematic view of an automatic control system forradioactive regional ventilation studies constructed in accordance withthe present invention;

FIG. 2 is a fragmentary enlarged plan view of a portion of the apparatusof FIG. 1;

FIG. 3 is an electrical circuit diagram illustrating a sequentialstepping switch arrangement forming part of the present invention; and

FIG. 4 is a perspective view of a control device constructed inaccordance with the present invention, said control device beingresponsive to depletion of a radioactive gas reservoir While only thepreferred forms of the invention have been illustrated in the drawings,it will be apparent that other modifications and changes could be madewithin the purview of the attached claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings indetail, it will be seen that the automatic control system of the presentinvention, basically includes a breathing device or mask 11 adapted forsealed communication with the breathing passages 12 of a living subject13, control valve means 14 having inlet and outlet passages 16 and 17,the control valve means 14 being formed to permit inhalation by thesubject 13 only from the inlet passage 16 and exhalation only throughthe outlet passage 17, a radioactive gas reservoir 18 capable of holdinga measured volume of gas at ambient pressure, a gas supply valve 19connecting said inlet passage 16 to the reservoir 18, an air supplyreservoir 21 capable of holding a measured volume of air at ambientpressure, an air supply valve 22 connecting inlet passage 16 toreservoir 21, an ambient air supply valve 23 connecting inlet passage 16to ambient air, an exhaust valve 26 connecting outlet passage 17 toconduit 24, and actuating means 27 operatively connected to the recitedvalves and formed for opening and closing these valves in a desiredsequence.

The control valve means 14 is shown schematically in FIG. 2 as includingcheck valves 28, 29 and 31 in the passages lead ing to the mask 11 fromvalves 19, 23 and 26, respectively. In FIG. 2, check valves 28 and 29permit air from reservoirs l8 and 21, and ambient air to enter mask 11through inlet passage 16, provided the associated valves 19, 22 or 23are open, but prevent reverse flow of air or gas. Likewise, check valve31 permits exhaled air to flow from mask 11 through outlet passage 17,provided valve 26 is open. Any suitable valve means which will permitinhalation from the inlet passage 16 and restrict exhalation to theoutlet passage 17 could be used. A commercial valve of this nature ismanufactured by W.E. Collins Co. and is identified by the part No.P-320.

Valve 19 is here connected through Y tubing to the reservoir 18 ofradioactive tagged air through a check valve 32. The capacity ofreservoir 18 is chosen to approximate the amount of air normally inhaledinto the lungs of the subject during a normal breath (usually about300cc). Valve 32 permits the radioactive tagged air to be removed fromthe reservoir 18, but prevents entry into reservoir 18 of thenonradioactive air from reservoir 23. Reservoir 21 contains anadditional volume of non-radioactive air approximating the volume of thebreathing passages of the subject between the mouth and the lungs(usually about 150cc).

Valves I9, 22, 23 and 26 are preferably provided with actuating deviceswhich may be remotely controlled. Should manual operation be desired, itmay be accomplished by solenoids or air actuators, controlled by aseries of interlocking push-buttons, or individual switches, or airvalves. A table listing the several switch positions and the resultingopen or closed state of the valves, is as follows:

The operator initiates the cycle by turning switch handle 41 on thecontrol box 42 to position 1 which opens valves 23 and 26, allowing thesubject to breath in ambient air through valve 23 and inlet passage 16,and to breath out through outlet passage 17 and exhaust valve 26, theexhaled air passing through a tube 43 to the exterior of the building.

During an exhalation, the operator moves switch handle 41 to position 2,closing ambient air supply valve 23 and opening radioactive gas supplyvalve 19 so that the next inhalation will draw the radioactive gas fromreservoir 18.

At the instant the radioactive gas reservoir 18 is empty, the operatormoves the switch handle 4 1 to position 3 which opens valve 22 to supplythe additional volume of nonradioactive air from reservoir 21. Position3 also closes the exhaust valve 26 and at the same instant supplieselectrical energy to close a relay 43 which starts the scintillationcamera or other radioactive recording device 44. The scintillationcamera 44 requires approximately 5 seconds to register the 15,000 countsnecessary for the print. The operator moves switch handle 41 to position4 to close valve 119 and, inasmuch as the valves 23 and 26 are alreadyclosed, the subject is unable to exhale or inhale further.

At the expiration of the approximately 5 second time-count interval, thescintillation camera 44 automatically shuts off and the operator movesswitch handle 41 to position 5, opening ambient air supply valve 23 andair exhaust valve 26 so the subject can resume normal breathing. Thus,switch settings 1 and 5 represent the same set of conditions.

Additional scintiphotos can be obtained at various time intervalsfollowing the initial tests, and under various conditions as selected bythe operator, if so desired. Such additional tests can be automaticallytimed and programmed into stepping switch 38.

Where a completely automatic sequence is desired, stepping switch 38 isdriven by timer 39, and the entire cycle is initiated by closing switch46. Obviously, the timer 39 should be adjusted to permit sufficient timeat each of the switch positions for the intended function to take place.

A modified form of the invention is illustrated in FIG. 4 wherein valve22 is opened automatically as soon as the contents of the radioactivegas reservoir are exhausted. The reservoirs 18a and 21a, correspondingto reservoirs 18 and 21 in FIG. 1, are provided in the form ofinflatable, flexible walled bags, such as rubber bags. Reservoir 18a issupported on a platform 51, to which a swingable arm 52 is pivoted tooverlie and rest upon reservoir 180 so that arm 52 swings upwardly asbag 18a is inflated and swings downwardly as bag 18a is deflated. Arm 52is in the position shown in solid lines at the beginning of the cyclewhen reservoir 18a is inflated. As the subject exhausts the contents ofreservoir 18a, the arm 52 drops under its own weight to the positionshown in dotted lines where the distal end of arm 52 actuates amicroswitch 53 to supply electrical current to open solenoid valve 22and allow the normal air contents of reservoir 21a to be supplied to thesubject.

From the foregoing it will be apparent that the automatic control systemfor radioactive regional ventilation studies of the present inventionprovides a novel method of conducting such studies and a novel apparatuscapable of manual or automatic use.

We claim:

1. An automatic control system for radioactive regional ventilationstudies, comprising a breathing device adapted for sealed communicationwith the breathing passages of a living subject,

a control valve means for said breathing device having inlet and outletpassages and being responsive to the breathing of the subject to permitinhalation by the subject only from said inlet passage and exhalationonly through said outlet passage,

a radioactive gas reservoir capable of holding a measured volume of gasat ambient pressure,

a gas supply valve connecting said inlet passage of said control valvemeans to said radioactive gas reservoir,

an air supply reservoir capable of holding a measured volume of air atambient pressure,

an air supply valve connecting said inlet passage of said control valvemeans to said air supply reservoir,

an ambient air supply valve connecting said inlet passage of saidcontrol valve means to ambient air,

an exhaust conduit,

an exhaust valve connecting said outlet passage of said control valvemeans to said exhaust conduit,

and actuating means operatively connected to said valves and formed foropening and closing said valves in a desired sequence.

2. An automatic control system as described in claim 1, and wherein saidactuating means further comprises an actuating mechanism for aradioactive recording device, with said actuating mechanism beingoperated at desired places in said sequence.

.3. An automatic control system as described in claim 1, and whereinsaid actuating means is formed to cycle automatically through saidsequence.

4. An automatic control system as described in claim 1, and wherein saidactuating means further comprises solenoid actuators for each of saidvalves, and switch means formed to provide electrical current to saidsolenoid actuators in said desired sequence.

5. An automatic control system as described in claim 4, and wherein saidswitch means includes a stepping switch, and a timing device for cyclingsaid stepping switch through said desired sequence in desired incrementsof time.

6. An automatic control system as described in claim 1, and wherein saidair supply valve is responsive to depletion of said radioactive gasreservoir.

7. An automatic control system as described in claim 6, and wherein saidradioactive gas reservoir comprises a flexible wall bag, a pivoted armrests on said bag and is formed to drop through an arc as radioactivegas is removed from said bag, said air supply valve is electricallyoperated, and a switch device is positioned to intercept said arm andsupply electrical current to said air supply valve so as to open thelatter when said arm drops a desired distance.

8. A method of conducting radioactive regional ventilation studies,comprising the steps of excluding ambient air from the breathingpassages of a subject,

supplying a measured quantity of radioactive tagged air equivalent tothe increase in normal volumetric capacity of the subjects lungs duringnormal breath of the subject, said radioactive tagged air beingdelivered at ambient air during said period of timed duration,

and permitting exhalation of said measured quantities of radioactivetagged air and additional air at the end of said period.

9. A method of conducting radioactive regional ventilation studies asdescribed in claim 8, and which comprises the additional steps ofventing the exhaled radioactive tagged air to the outside.

1. An automatic control system for radioactive regional ventilationstudies, comprising a breathing device adapted for sealed communicationwith the breathing passages of a living subject, a control valve meansfor said breathing device having inlet and outlet passages and beingresponsive to the breathing of the subject to permit inhalation by thesubject only from said inlet passage and exhalation only through saidoutlet passage, a radioactive gas reservoir capable of holding ameasured volume of gas at ambient pressure, a gas supply valveconnecting said inlet passage of said control valve means to saidradioactive gas reservoir, an air supply reservoir capable of holding ameasured volume of air at ambient pressure, an air supply valveconnecting said inlet passage of said control valve means to said airsupply reservoir, an ambient air supply valve connecting said inletpassage of said control valve means to ambient air, an exhaust conduit,an exhaust valve connecting said outlet passage of said control valvemeans to said exhaust conduit, and actuating means operatively connectedto said valves and formed for opening and closing said valves in adesired sequence.
 2. An automatic control system as described in claim1, and wherein said actuating means further comprises an actuatingmechanism for a radioactive recording device, with said actuatingmechanism being operated at desired places in said sequence.
 3. Anautomatic control system as described in claim 1, and wherein saidactuating means is formed to cycle automatically through said sequence.4. An automatic control system as described in claim 1, and wherein saidactuating means further comprises solenoid actuators for each of saidvalves, and switch means formed to provide electrical current to saidsolenoid actuators in said desired sequence.
 5. An automatic controlsystem as described in claim 4, and wherein said switch means includes astepping switch, and a timing device for cycling said stepping switchthrough said desired sequence in desired increments of time.
 6. Anautomatic control system as described in claim 1, and wherein said airsupply valve is responsive to depletion of said radioactive gasreservoir.
 7. An automatic control system as described in claim 6, andwherein said radioactive gas reservoir comprises a flexible wall bag, apivoted arm rests on said bag and is formed to drop through an arc asradioactive gas is removed from said bag, said air supply valve iselectrically operated, and a switch device is positioned to interceptsaid arm and supply electrical current to said air supply valve so as toopen the latter when said arm drops a desired distance.
 8. A method ofconducting radioactive regional ventilation studies, comprising thesteps of excluding ambient air from the breathing passages of a subject,supplying a measured quantity of radioactive tagged air equivalent tothe increase in normal volumetric capacity of the subject''s lungsduring normal breath of the subject, said radioactive tagged air beingdelivered at ambient air pressure to the breathing passages of thesubject for inhalation into the lungs, supplying an measured quantity ofadditional air to said breathing passages equivalent to the tidal volumethereof so as to concentrate said radioactive tagged air in the lungs,preventing exhalation of said measured quantities of radioactive taggedair and additional air for a period of timed duration, making a visualrecord of the lungs by radioactive recording during said period of timedduration, and permitting exhalation of said measured quantities ofradioactive tagged air and additional air at the end of said period. 9.A method of conducting radioactive regional ventilation studies asdescribed in claim 8, and which comprises the additional steps ofventing the exhaled radioactive tagged air to the outside.